Organisms Commons^™

Disruption Of Insertion Sequence 200 (Is200) Leads To A Premature Induction Of The Cysteine Regulon In Salmonella Typhimurium, Naomi-Jean Q. Scherba

Electronic Thesis and Dissertation Repository

Salmonella Typhimurium is a leading contributor to non-typhoid diseases with complex regulatory networks that are key to understanding its pathogenicity and virulence. I explore the role of the sRNA IS200, where its deletion in Salmonellaleads to premature induction of the Cys regulon. The premature induction in ∆IS200 was validated through qRT-PCR and GFP transcriptional fusions and occurs at late exponential to early stationary phase. In addition, ∆IS200 leads to increased sensitivity to oxidative stress. The focus of this work has been to understand how ∆IS200 leads to premature Cys regulon induction, and I present three models: the futile import/export, …

The Development Of Bacterial Magnetic Resonance Imaging For Microbiota Analyses, Sarah C. Donnelly

Electronic Thesis and Dissertation Repository

Current microbial analyses to assess either the commensal microbiota or microorganism infection and disease typically require ex vivo techniques that risk contamination and are not undertaken in real time. The possibilities for employing imaging techniques in the microbiology field is becoming more prominent as studies expand on the use of positron emission tomography, ultrasound and numerous microscopy techniques. However, magnetic resonance imaging (MRI), a non-invasive in vivo modality that can produce real-time results is falling behind. Here, we examined the feasibility of detecting bacteria using clinical field strength MRI. Commensal, probiotic and uropathogenic Escherichia coli were scanned by 3 Tesla …

Synergistic Effects Of Non Contact Induction Heating & Antibiotics On Staphylococcus Aureus Biofilm, Rajeshwar Singh Sidhu

Electronic Thesis and Dissertation Repository

Staphylococcus aureus is a major cause of prosthetic joint infection (PJI) in which it forms adherent biofilms, thick aggregates of extracellular polymeric substances (EPS) produced by the bacteria. Biofilm associated infections are difficult to treat as they have increased resistance to various antimicrobial agents, which means infected implants often require multiple procedures and prolonged antibiotic therapy. However, a new and emerging method of treatment of PJI is non-contact induction heating (NCIH) of metal implants. We sought to investigate the feasibility and effectiveness of NCIH along with synergistic effects of antibiotics (Vancomycin) in reducing bacterial load within surface associated biofilms in …

Elucidating The Importance Of Hope And Its Potential Lewis Glycosylation In Helicobacter Pylori, Keertika Yogendirarajah

Electronic Thesis and Dissertation Repository

Helicobacter pylori colonizes 50% of the world’s population, whereby glycoproteins and Lewis Y-containing lipopolysaccharides contribute to its pathogenesis. We investigated whether the HopE porin is glycosylated, if the glycan is Lewis Y, and if this is mediated by the putative oligosaccharide transferase HP0946 or the O-antigen ligase WaaL. Western blotting was performed on outer membranes with anti-HopE antibodies, anti-Lewis Y antibodies and fucose-binding BambL lectin to ascertain HopE glycosylation. We discovered that HopE is likely glycosylated by a non-Lewis Y fucose-containing glycan and neither HP0946 nor WaaL are the transferase. Additionally, we investigated HopE’s role in antibiotic susceptibility via Etest …

Carbohydrates And Fungal Toxin Exposure Influence The Vaginal Microbiota, Metabolome, And Reproductive Health Of Women, Stephanie L. Collins

Electronic Thesis and Dissertation Repository

The reproductive health of women is influenced by microorganisms and their metabolites, namely those representing the vaginal microbiota and those producing toxins that are ingested. To manipulate the vaginal microbiota toward a health-associated, Lactobacillusdominant state, an approach adopting prebiotic lactulose was taken. Using batch culture, lactulose supported Lactobacillus maintenance and positively altered metabolites, while not disrupting indigenous L. crispatus epithelial adherence. The vagina also harbours abundant glycogen, but initial assumptions that lactobacilli utilize it were incorrect. I have now shown that glycogen selectively stimulates organisms associated with dysbiosis and L. iners in a self-limiting manner. Other compounds such as environmental …

Investigating The Regulation Of A Fatty Acid Efflux Pump In Methicillin Resistant Staphylococcus Aureus, James Et Schneider

Electronic Thesis and Dissertation Repository

Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) strain USA300 has rapidly achieved pandemic status in the community setting. To persist on human hosts, USA300 requires mechanisms to overcome innate immune defenses of the skin, which include antimicrobial unsaturated free fatty acids (uFFAs). This study evaluated efflux mediated mechanisms of resistance to uFFA. tet38 encoding an efflux pump that was previously implicated in resistance to palmitoleic acid, was found to have no role in resistance to uFFA. Conversely, the farE encoded efflux pump conferred resistance to linoleic and arachidonic acid, but not palmitoleic acid. farE expression was induced by uFFA, but …

Granulocyte Colony-Stimulating Factor: Its Role In Gut-Homing Macrophage Generation And Colitis, And Production By Probiotics, Shahab Meshkibaf

Electronic Thesis and Dissertation Repository

The pleiotropic cytokine granulocyte-colony stimulatory factor (G-CSF) is mainly required for the generation of neutrophils, but its role in macrophage generation has also been reported. In addition, G-CSF is effective for the down-regulation of inflammatory cytokines and ameliorating gut disorders, such as colitis. However, the G-CSF function in macrophage generation and gut immunity remains unclear. The first focus of this thesis was to assess the role of G-CSF in macrophage generation and its contribution to gut immunity. G-CSF was found to promote the generation of Gr-1high/F4/80+ macrophages in macrophage (M)-CSF-treated bone marrow cells, most likely through suppressing cell death. Gr-1high …

Response Of Soil Nitrification To The Veterinary Pharmaceuticals Monensin, Ivermectin And Zinc Bacitracin, Magda A. Konopka

Electronic Thesis and Dissertation Repository

Pharmaceutical residues can reach agricultural land through amendment with animal or human waste. Since 2010, a series of replicated plots received annual applications of ivermectin, monensin and zinc bacitracin, either singly or in a mixture, at 0.1 mg/kg and 10 mg/kg concentrations. I collected soil samples before and after the fourth annual application of pharmaceuticals and assayed them for functional changes and amoA gene abundance, a gene needed for ammonia oxidation. In 2013, I exposed the soils to 100 mg/kg in a laboratory experiment which resulted in acceleration of nitrification. Under 10 mg/kg treatments in the field the abundance of …

Efficacy Of Novel Antifouling/Antimicrobial Coatings For The Prevention Of Urinary Device Associated Infection And Encrustation, Thomas O. Tailly

Electronic Thesis and Dissertation Repository

Device associated urinary tract infections are a very important healthcare issue. Despite best efforts in preventing and treating these infections, many patients and physicians are still confronted with this problem. Our research group is involved in testing and evaluating new stent coatings for the prevention of device associated infections and device encrustation. In the current project, we tested two new coating copolymers, both based on a long chain polymer backbone and mussel adhesive protein to this purpose in a rabbit and porcine model. The results demonstrate efficiency of one copolymer in preventing infections in the rabbit model. Interestingly there is …

Cell Biology Of The Entry Of Bdellovibrio And Like Organisms, Ryan M. Chanyi

Electronic Thesis and Dissertation Repository

Bdellovibrio and like organisms (BALOs) are obligate predators of Gram negative bacteria. Predation occurs via a periplasmic or epibiotic life cycle. A periplasmic predator invades the periplasmic space of a prey while an epibiotic predator remains on the exterior.

An analysis of the genome sequences of periplasmic predators, Bdellovibrio bacteriovorus and Bacteriovorax marinus, and epibiotic predators, Bdellovibrio exovorus and Micavibrio aeruginosavorus determined that the genome size of epibiotic predators was smaller, while the metabolic networks were highly conserved. No core set of invasion-specific genes was identified.

Both life cycles were characterized by cryoelectron microscopy. The periplasmic predator, Bd. bacteriovorus …

Characterization Of Staphylococcus Aureus Lipase, Vithooshan Vijayakumaran

Electronic Thesis and Dissertation Repository

USA300, a strain of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), has become prevalent in the community. Colonization of human skin requires mechanisms that allow this bacterium to overcome the innate immune defenses on the skin, including secretion of antimicrobial lipids. Antimicrobial lipids inhibit S. aureus growth and induce the staphylococcal proteolytic cascade, producing aureolysin (Aur) which processes the lipase glycerol ester hydrolase (Geh). Nearly all S. aureus strains secrete Geh, yet little information exists concerning its function. Using purified Aur and Geh we confirm that aureolysin processes proGeh to Geh. We then confirmed that geh was required for lipase activity …

Systematic Assessment Of The Contribution Of Superantigens To Nasopharyngeal Colonization In A Mouse Model Of Streptococcal Infection, Katherine J. Kasper

Electronic Thesis and Dissertation Repository

Streptococcus pyogenes is adapted for persistence in humans. It typically colonizes the tonsils and skin, and humans are the only known reservoir. S. pyogenes can cause a wide range of mild to serious infections. Most streptococci-related deaths are due to complications of rheumatic fever and invasive infections. S. pyogenes produces virulence factors that contribute to the pathogen’s ability to colonize and cause disease, including streptococcal superantigens (SAgs), also known as streptococcal pyrogenic exotoxins (Spes). SAgs function by cross-linking T cells and antigen presenting cells (APC) which may cause a massive inflammatory response, and as such have been found to contribute …